JPH05336667A - Reverse charge preventive unit - Google Patents

Abstract

PURPOSE:To provide a reverse charge preventive unit which can stop operation of a distributed power supply system positively upon opening of a substation circuit breaker even when power generation of the distributed power supply system and power consumption of load are in equilibrium state. CONSTITUTION:A high voltage distribution line 1 interconnected with distributed power supply systems 4, 5 while allowing reverse power flow is provided with a three-phase short circuit unit 9 including a contact or noncontact switch for forcibly short-circuiting the high voltage distribution line 1 upon function of a substation circuit breaker thus collapsing equilibrium state of the system forcibly. Since the distributed power supply systems 4, 5 can detect variation of the system, operation thereof can be stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse charge prevention device used in a system in which a distributed power system such as a solar cell or a wind power generator is connected to a low voltage distribution line or a high voltage distribution line. .

[0002]

2. Description of the Related Art In a system in which a distributed power supply system is connected to a low voltage distribution line or a high voltage distribution line, even if the substation breaker is opened due to an accident or construction, In order to prevent the reverse charging phenomenon in which the voltage remains in the grid due to the islanding operation, it is necessary to stop the distributed power supply system at the same time as the operation of the substation breaker. For this reason, conventionally, a method has been considered in which the distributed power supply system detects voltage fluctuations and frequency fluctuations that occur in the grid due to the opening of the substation breaker, and the operation is automatically stopped.

However, when the power generation output of the distributed power supply system and the power consumption of the load are in equilibrium and power is not being substantially fed from the substation side, the substation circuit breaker opens. Even if the battery is damaged, the distributed power supply system cannot detect the voltage fluctuation and the frequency fluctuation of the system, and there is a risk that the above-mentioned reverse charging phenomenon occurs by continuing the operation as it is.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and prevents the reverse charging phenomenon due to the isolated operation of the distributed power supply system. Therefore, the power generation output and load consumption of the distributed power supply system are consumed. It has been completed to provide a reverse charge prevention device that can reliably stop the operation of the distributed power supply system when the substation circuit breaker is opened even when the electric power and the electric power are in a balanced state. .

[0005]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above problems, provides a high voltage distribution line in which a distributed power supply system is interconnected with a reverse power flow in a grid and a substation circuit breaker. It is characterized in that a three-phase short-circuit device including a non-contact or a contact switch for forcibly short-circuiting the high-voltage distribution line in three phases when operating is provided.

[0006]

According to the present invention, when the substation breaker is opened for some reason, the contactless switch or the contact switch is instantly turned on to forcibly bring the high-voltage distribution line into a three-phase short-circuited state. As a result, even if the system load and the output of the distributed power supply system are in a balanced state, the balance will momentarily be disrupted, so the distributed power supply system can reliably ensure system voltage fluctuations and frequency fluctuations. It can detect and stop its operation. Therefore, it is possible to prevent the above-mentioned reverse charging phenomenon.

[0007]

The present invention will be described in more detail with reference to the embodiments shown in the drawings. 1 and 2 show a first embodiment of the present invention. In FIG. 1, 1 is a high voltage distribution line, 2 is a pole transformer, and 3 is a low voltage distribution line. In this embodiment, the distributed power supply system 4 is connected to the high voltage distribution line 1, and the distributed power supply system 5 is connected to the low voltage distribution line 3 together with the load 6. These distributed power system 4,
Reference numeral 5 denotes, for example, a solar cell system or a wind power generation system, which is configured to automatically stop the system when voltage fluctuations or frequency fluctuations of the grid are detected.

A three-phase short circuit device 9 including a switch 7 and a switch control device 8 is connected to the high-voltage distribution line 1. The switch 7 may be a contactless switch such as a thyristor or a mechanical contact switch. The switch controller 8 is connected to a substation breaker 11 by a communication cable 10 as shown in FIG.

In this embodiment, when the substation breaker 11 is opened for some reason, the signal is transmitted to the switch control device 8 via the communication cable 10, and the switch control device 8 turns on each switch 7. The high-voltage distribution line 1 is instantly brought into a three-phase short circuit state. As a result, the voltage of the high-voltage distribution line 1 obviously decreases, and this fluctuation is also transmitted to the low-voltage distribution line 3. Therefore, even if the output of the distributed power supply systems 4 and 5 is balanced with the power consumption of the load 6, the distributed power supply systems 4 and 5 connected to the high-voltage distribution line 1 and the low-voltage distribution line 3 are It is possible to reliably detect voltage fluctuations in the grid and automatically stop its operation. Therefore, when the substation circuit breaker 11 opens, the system voltage disappears almost at the same time, and the danger of the reverse charging phenomenon is prevented.

In the above-described first embodiment, the three-phase short circuit device 9
One is provided on the downstream side of the substation circuit breaker 11. In this case, if any of the switches 12 shown in FIG. 2 is opened, the three-phase short-circuit device 9 is operated. The voltage fluctuation of the high-voltage distribution line 1 does not reach the downstream side of the switch 12, and there is a risk that a reverse charging phenomenon will occur in that range. Therefore, in the second embodiment shown in FIG. 3, a three-phase short-circuit device 9 is provided for each switch 12 arranged at a predetermined interval in the high-voltage distribution line 1 and all three lines are opened at the same time as the substation circuit breaker 11 is opened. The phase short-circuit device 9 is turned on. As a result, even if the switch 12 is opened midway, the equilibrium state on the downstream side can be broken, and the reverse charging phenomenon is prevented.

In each of the above-mentioned embodiments, since the communication cable 10 for operating the three-phase short-circuit device 9 is connected to the substation circuit breaker 11, in particular, as in the second embodiment, a large number of three-phase short-circuit devices 9 are connected. When arranged, it is necessary to provide a large number of communication cables 10 over a long distance. Therefore, in the third embodiment shown in FIG. 4, the communication cable 10 for operating the three-phase short-circuit device 9 is connected to the switch 12 immediately before it. Generally, the control system is configured such that these switches 12 are opened in conjunction with each other when the substation circuit breaker 11 is opened. Therefore, when the switch 12 is opened, the three-phase short circuit device 9 is connected.
Is operated, it is possible to obtain the same effect as that of the second embodiment without providing a large number of communication cables 10 with the substation breaker 11.

However, when all the three-phase short-circuit devices 9 are linked with the switch 12, the switch 12 is opened even if the substation circuit breaker 11 is opened because the voltage remains on the high-voltage distribution line 1 due to the reverse charging phenomenon. If the switch does not open (generally, the switch does not open when voltage or overcurrent is present in the distribution line), the three-phase short-circuit device 9 does not operate. For this reason, as shown in FIG. 4, only the first three-phase short-circuit device 9 behind the substation circuit breaker 11 is made to interlock with the substation circuit breaker 11.

[0013]

As described above, according to the present invention, the high-voltage distribution line is provided with a contactless switch or a contact switch for forcibly short-circuiting the high-voltage distribution line in three phases when the substation breaker operates. Even if the power generation output of the distributed power supply system and the power consumption of the load are in a balanced state, the substation circuit breaker is opened and the balanced state is instantaneously destroyed to ensure the operation of the distributed power system. It can be stopped. Therefore, the present invention has a great contribution to the industrial development as a reverse charge prevention device capable of surely preventing the reverse charge phenomenon.

[Brief description of drawings]

FIG. 1 is a three-phase connection diagram showing a first embodiment.

FIG. 2 is a system diagram showing a first embodiment.

FIG. 3 is a system diagram showing a second embodiment.

FIG. 4 is a system diagram showing a third embodiment.

[Explanation of symbols]

 1 High-voltage distribution line 2 Pole transformer 3 Low-voltage distribution line 4 Distributed power system 5 Distributed power system 6 Load 7 Switch 8 Switch control device 9 Three-phase short-circuit device 10 Communication cable 11 Substation circuit breaker 12 Switch

Claims (1)

[Claims] 1. A high-voltage distribution line in which a distributed power supply system is interconnected with a reverse flow in the system, and a non-contact or forcibly short-circuiting the high-voltage distribution line by three-phase when the substation circuit breaker operates. A reverse charge prevention device comprising a three-phase short-circuit device including a contact switch.